Skip to main content

Mason Thorson Ells Levee Rehabilitation Project

Information about project that will repair a damaged levee on the Middle Fork Snoqualmie River.

Project overview

The Mason Thorson Ells Levee is located on western bank of the Middle Fork Snoqualmie River near the City of

North Bend. A flood in February 2020 damaged part of the downstream end of the Mason Thorson Ells Levee. This created a flood and erosion risk that threatens the safety of the nearby community, properties and roads.

King County, as the primary service provider to the King County Flood Control District, is partnering with the U.S. Army Corps of Engineers (Corps of Engineers) to repair the levee. Repairs are planned for 2023, using 80% federal and 20% local funds. Construction will include regrading and adding rock to the eroded bank, as well as adding plants to help further stabilize the slope and area behind the levee.

King County sought input from local recreational groups, the City of North Bend, and other stakeholders on the project design and outreach plans. This input informed County comments to the Corps of Engineers and the County’s public notification plans. The project is expected to be completed by October 2023.

What is a levee?

A levee is a raised structure built along a riverbank to contain, control, or divert the flow of water and protect the land along the river from temporary flooding. A levee is usually made of earth and runs parallel to the course of a river. 

Project goal

  • Repair and stabilize active erosion at the downstream end of Mason Thorson Ells Levee. 

Project schedule

Activity Date
Corps of Engineers Design and National Environmental Policy Act (NEPA) Process
2020 to 2023
Construction Between Sept. 11-Sept. 30, 2023
Site monitoring Ongoing

Construction impacts

King County is working to limit the impacts of construction.  The project site at the downstream end of the levee will be inaccessible during construction. However, construction will not block passage on the water. A memorial bench will be temporarily moved during construction and replaced in the same location when the project is done. A large sequoia tree and two smaller trees are too close to the damaged area and will have to be removed to safely make the repairs to the levee. In their place, nine new trees will be planted behind the levee on public land. The trees will enhance habitat for fish and wildlife.

We will update this webpage with further impacts to roads, sidewalks, trails, or parks in the area as the project moves through design and permitting. We will also post signs and flyers near the project site and notify local businesses and residents before and during construction. To receive updates, please sign up for project announcements.